City scout Rob Newman made a trip to Portugal last week, where he watched Argentina centre-half Otamendi and long-term target Eliaquim Mangala impress in a 3-1 win over Sporting Lisbon.

City made enquiries for the €40 million-rated Mangala in the summer and although the Premier League side maintain an interest in the France international, the 25-year-old Otamendi has become the priority for manager Manuel Pellegrini.

Porto value the defender at €30m and, with City having made an indifferent start to the new season - despite bringing in new talent to the tune of over €100m - the club are prepared to open their cheque book again.

Without captain Vincent Kompany, who is yet to recover from a thigh injury which could keep him out of his side’s next three games, City have looked vulnerable defensively, particularly away from home, where they have already lost on three occasions.

Pellegrini tried to bolster his defensive ranks over the summer but failed in his attempt to tempt Real Madrid centre-half Pepe to Etihad Stadium, while the club also made enquiries for Mangala.

Ultimately, City managed to sign only 32-year-old Martin Demichelis on a two-year deal from Atletico Madrid on deadline day, and with no talks planned to extend the contract of Joleon Lescott, whose deal expires in the summer, the club are ready to spend when the window reopens in January.